I probably believe, they are somewhere between 16 to 17%.
The better part is, many of them are well educated now and understand the benefit of keeping small family. So during next decade, the growth rate would be slow for Indian Muslims.
With education and rubbing shoulders with equally good fellow colleagues, their level and quality of life is also increasing.
On lighter note, my badminton partner is muslim and pHD holder from a reputed university. I will miss this year's iftar and ramzan eid celebrations at his place. He along with his family was at our place for Diwali celebrations..